1. Spontaneous chemical reactions
A. have a negative

G value.
B. create additional energy.
C. never require a catalyst.
D. are usually endergonic.
E. happen quickly in a test tube.
2. Which one of the following statements in NOT an accurate description of a catalyst?
A. Catalysts increase the rate of a chemical reaction.
B. Catalysts are considered to be one of the reactants of the chemical reaction.
C. Catalysts do not shift the equilibrium of a chemical reaction.
D. Catalysts decrease the amount of activation energy needed for a chemical reaction to occur.
E. Catalysts may be proteins.
3. The equilibrium constant for a chemical reaction is determined by
A. the initial substrate concentration.
B. the

G for the reaction.
C. the activation energy for the reaction.
D. the enzyme concentration.
E. the amount of heat available.
4. Endergonic reactions
A. are commonly regulated by feedback inhibition.
B. never happen in a cell.
C. can be catalyzed by an enzyme.
D. are generally spontaneous.
E. always happen at a slow rate.
5. The presence of a catalyst changes which one of the following characteristics of a chemical reaction?
A.

G
B. Substrate Energy
C. Product Energy
D. Activation Energy
E. Equilibrium
6. Addition of an enzyme can change which characteristic of a chemical reaction?
A. Change in free energy
B. Equilibrium constant
C. Activation energy
D. Michaelis constant
E. Substrate energy

7. In the lab, we looked at the reaction of pyrocatechol

quinone, catalyzed by the enzyme tyrosinase.
We were able to easily follow the progress of this reaction because the quinone was brown.
7A. Is the pyrocatechol

quinone spontaneous or nonspontaneous? Or can we tell? Please explain your answer.
We can’t tell. We only looked at initial velocities not at final equilibrium points or whether energy was released or absorbed.
7B. When we were getting ready for lab this week, we found the bottle of pyrocatechol that we used in this class last fall (6 months ago). Even though there was no enzyme in the bottle, the solution had turned brown. Please briefly explain why the solution turned brown.
The reaction proceeds even in the absence of the enzyme. It’s just that without the enzyme it runs very slowly so it takes months to see the product. With the enzyme, the product shows up in seconds.
8. The reaction 2 NH
3

N
2
+ 3 H
2
is endergonic. On the graph below, draw the energy diagram for this reaction. Show what corresponds to the

G value on the diagram.
Is this reaction chemically spontaneous or nonspontaneous? How do you know? nonspontaneous. Endergonic reactions are always nonspontaneous
This reaction can be catalyzed by the addition of iron. Does adding the catalyst change this energy diagram? If so, draw a dashed line and explain how you knew where to draw it. If not, explain why not.
The activation energy is lower but the

G
Free
Energy value is unchanged.
Instead of adding iron, this reaction can be speeded up by adding heat. Does adding
Progress of the Reaction heat change this energy diagram? If so, draw a dotted line and explain how you knew where to draw it. If not, explain why not.
No, heat doesn’t change the energy diagram. It just means that more ammonia molecules have enough energy to make it over the activation energy hurdle.
9. All catalysts
A. are enzymes.
B. increase the rate of the reaction.
C. increase the K eq
of the reaction.
D. decrease the K eq
of the reaction.
E. briefly violate the First Law of Thermodynamics.
10A. Triglycerides are synthesized when fatty acids are added to what three-carbon molecule?
3 Fatty Acids + __ glycerol _________ Triglyceride + H
2
O

10B. The  G for this reaction is -5 kcal/mole and the activation energy (E
A
) is 2 kcal/mole. Circle each term below that correctly describes this reaction.
Condensation
Isogonic
Endergonic Exergonic
Nonspontaneous
Hydrolysis
Spontaneous
10C. Draw the energy diagram for this reaction in the chart on the left. Be sure to label your axes.
(4 points)
G
10D. Now, suppose we add the enzyme Acyltransferase which catalyzes this reaction. Use a dashed line to show how the enzyme changes the energy diagram. Also record the new  G and E
A
(with units!).
4
2
6
10
8
Progress of the Reaction
 G = __ -5kcal/mol ________ E
A
= ___ 1 kcal/mole _________
10E. When this reaction reaches equilibrium without the enzyme, which statement is true? Circle one.
No fatty acids are present
Few fatty acids are present
Equal amounts of fatty acids and triglycerides are present
Few triglycerides are present
No triglycerides are present
Can’t tell for certain
10F. When this reaction reaches equilibrium with the enzyme, which statement is true? Circle one.
No fatty acids are present
Few fatty acids are present
Equal amounts of fatty acids and triglycerides are present
Few triglycerides are present
No triglycerides are present
Can’t tell for certain
10G. The enzyme Acyltransferase would be expected to be in which organelle?
___ Smooth Endoplasmic Reticulum ______
10H. The K eq
value for this reaction is…
Greater than one
Equal to one
Less than one
Can’t tell
11. Sucrase catalyzes the breakdown of sucrose into glucose and fructose effeciently at a neutral pH.
Substantially raising the pH of the reaction changes some of the aspects of that reaction and leaves others unchanged.
Will raising the pH affect the

G of the reaction? Please explain.

No. This may denature the enzyme, but since the enzyme has no effect on the

G, the denaturation of the enzyme will also have no effect on the

G.
Will raising the pH affect the primary structure of the enzyme? Please explain.
No. The primary structure is simple the order in which the amino acids are connected by covalent peptide bonds. Denaturation will not affect these covalent bonds.
Will raising the pH affect the tertiary structure of the enzyme? Please explain.
Yes. A higher pH will affect the ability of the protein to form intramolecular ionic interactions and thus lead to the protein’s denaturation (or loss of three-dimensional structure).